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    <script>
        //对非布尔值进行！操作会先转换为布尔值再操作
        var a =12;
        var b= !a;
        console.log(typeof b);
        console.log(b);

        //对一个布尔值进行！！操作会将该值转化为布尔值
        var c =!!123;
        var d =!!!113;
        console.log(c);
        console.log(d);

        

    </script>   
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